refactor: rework init_tracing to avoid unused variable

... when feature `telemetry-otlp` is not enabled
move feature management into tracing_setup module to make the server code cleaner.

src/garage/main.rs

@@ -7,7 +7,6 @@ extern crate tracing;
 mod cli;
 mod secrets;
 mod server;
-#[cfg(feature = "telemetry-otlp")]
 mod tracing_setup;
 
 #[cfg(not(any(feature = "bundled-libs", feature = "system-libs")))]

src/garage/server.rs

@@ -15,8 +15,7 @@ use garage_web::WebServer;
 use garage_api_k2v::api_server::K2VApiServer;
 
 use crate::secrets::{fill_secrets, Secrets};
-#[cfg(feature = "telemetry-otlp")]
-use crate::tracing_setup::*;
+use crate::tracing_setup::init_tracing;
 
 async fn wait_from(mut chan: watch::Receiver<bool>) {
 	while !*chan.borrow() {
@@ -54,12 +53,7 @@ pub async fn run_server(config_file: PathBuf, secrets: Secrets) -> Result<(), Er
 
 	if let Some(admin_trace_sink) = &config.admin.trace_sink {
 		info!("Initialize tracing...");
-
-		#[cfg(feature = "telemetry-otlp")]
 		init_tracing(admin_trace_sink, garage.system.id)?;
-
-		#[cfg(not(feature = "telemetry-otlp"))]
-		error!("Garage was built without OTLP exporter, admin.trace_sink is ignored.");
 	}
 
 	info!("Initialize Admin API server and metrics collector...");

src/garage/tracing_setup.rs

@@ -1,37 +1,53 @@
-use std::time::Duration;
+pub use telemetry::init_tracing;
 
-use opentelemetry::sdk::{
-	trace::{self, IdGenerator, Sampler},
-	Resource,
-};
-use opentelemetry::KeyValue;
-use opentelemetry_otlp::WithExportConfig;
+#[cfg(not(feature = "telemetry-otlp"))]
+mod telemetry {
+	use garage_util::data::Uuid;
+	use garage_util::error::Error;
 
-use garage_util::data::*;
-use garage_util::error::*;
-
-pub fn init_tracing(export_to: &str, node_id: Uuid) -> Result<(), Error> {
-	let node_id = hex::encode(&node_id.as_slice()[..8]);
-
-	opentelemetry_otlp::new_pipeline()
-		.tracing()
-		.with_exporter(
-			opentelemetry_otlp::new_exporter()
-				.tonic()
-				.with_endpoint(export_to)
-				.with_timeout(Duration::from_secs(3)),
-		)
-		.with_trace_config(
-			trace::config()
-				.with_id_generator(IdGenerator::default())
-				.with_sampler(Sampler::AlwaysOn)
-				.with_resource(Resource::new(vec![
-					KeyValue::new("service.name", "garage"),
-					KeyValue::new("service.instance.id", node_id),
-				])),
-		)
-		.install_batch(opentelemetry::runtime::Tokio)
-		.ok_or_message("Unable to initialize tracing")?;
-
-	Ok(())
+	pub fn init_tracing(_: &str, _: Uuid) -> Result<(), Error> {
+		error!("Garage was built without OTLP exporter, admin.trace_sink is ignored.");
+		Ok(())
+	}
+}
+
+#[cfg(feature = "telemetry-otlp")]
+mod telemetry {
+	use std::time::Duration;
+
+	use opentelemetry::sdk::{
+		trace::{self, IdGenerator, Sampler},
+		Resource,
+	};
+	use opentelemetry::KeyValue;
+	use opentelemetry_otlp::WithExportConfig;
+
+	use garage_util::data::*;
+	use garage_util::error::*;
+
+	pub fn init_tracing(export_to: &str, node_id: Uuid) -> Result<(), Error> {
+		let node_id = hex::encode(&node_id.as_slice()[..8]);
+
+		opentelemetry_otlp::new_pipeline()
+			.tracing()
+			.with_exporter(
+				opentelemetry_otlp::new_exporter()
+					.tonic()
+					.with_endpoint(export_to)
+					.with_timeout(Duration::from_secs(3)),
+			)
+			.with_trace_config(
+				trace::config()
+					.with_id_generator(IdGenerator::default())
+					.with_sampler(Sampler::AlwaysOn)
+					.with_resource(Resource::new(vec![
+						KeyValue::new("service.name", "garage"),
+						KeyValue::new("service.instance.id", node_id),
+					])),
+			)
+			.install_batch(opentelemetry::runtime::Tokio)
+			.ok_or_message("Unable to initialize tracing")?;
+
+		Ok(())
+	}
 }